chat_session/resource_manager.py

"""

Resource Manager for Flare

==========================

Manages lifecycle of all session resources

"""
import asyncio
from typing import Dict, Any, Optional, Callable, Set
from datetime import datetime, timedelta
from dataclasses import dataclass, field
import traceback
from enum import Enum

from .event_bus import EventBus, Event, EventType
from utils.logger import log_info, log_error, log_debug, log_warning


class ResourceType(Enum):
    """Types of resources managed"""
    STT_INSTANCE = "stt_instance"
    TTS_INSTANCE = "tts_instance"
    LLM_CONTEXT = "llm_context"
    AUDIO_BUFFER = "audio_buffer"
    WEBSOCKET = "websocket"
    GENERIC = "generic"


@dataclass
class Resource:
    """Resource wrapper with metadata"""
    resource_id: str
    resource_type: ResourceType
    session_id: str
    instance: Any
    created_at: datetime = field(default_factory=datetime.utcnow)
    last_accessed: datetime = field(default_factory=datetime.utcnow)
    disposal_task: Optional[asyncio.Task] = None
    cleanup_callback: Optional[Callable] = None

    def touch(self):
        """Update last accessed time"""
        self.last_accessed = datetime.utcnow()

    async def cleanup(self):
        """Cleanup the resource"""
        try:
            if self.cleanup_callback:
                if asyncio.iscoroutinefunction(self.cleanup_callback):
                    await self.cleanup_callback(self.instance)
                else:
                    await asyncio.to_thread(self.cleanup_callback, self.instance)

            log_debug(
                f"🧹 Resource cleaned up",
                resource_id=self.resource_id,
                resource_type=self.resource_type.value
            )
        except Exception as e:
            log_error(
                f"❌ Error cleaning up resource",
                resource_id=self.resource_id,
                error=str(e)
            )


class ResourcePool:
    """Pool for reusable resources"""

    def __init__(self,

                 resource_type: ResourceType,

                 factory: Callable,

                 max_idle: int = 10,

                 max_age_seconds: int = 300):
        self.resource_type = resource_type
        self.factory = factory
        self.max_idle = max_idle
        self.max_age_seconds = max_age_seconds
        self.idle_resources: List[Resource] = []
        self.lock = asyncio.Lock()

    async def acquire(self, session_id: str) -> Any:
        """Get resource from pool or create new"""
        async with self.lock:
            # Try to get from pool
            now = datetime.utcnow()
            while self.idle_resources:
                resource = self.idle_resources.pop(0)
                age = (now - resource.created_at).total_seconds()

                if age < self.max_age_seconds:
                    # Reuse this resource
                    resource.session_id = session_id
                    resource.touch()
                    log_debug(
                        f"♻️ Reused pooled resource",
                        resource_type=self.resource_type.value,
                        age_seconds=age
                    )
                    return resource.instance
                else:
                    # Too old, cleanup
                    await resource.cleanup()

        # Create new resource
        if asyncio.iscoroutinefunction(self.factory):
            instance = await self.factory()
        else:
            instance = await asyncio.to_thread(self.factory)

        log_debug(
            f"🏗️ Created new resource",
            resource_type=self.resource_type.value
        )
        return instance

    async def release(self, resource: Resource):
        """Return resource to pool"""
        async with self.lock:
            if len(self.idle_resources) < self.max_idle:
                resource.session_id = ""  # Clear session
                self.idle_resources.append(resource)
                log_debug(
                    f"📥 Resource returned to pool",
                    resource_type=self.resource_type.value,
                    pool_size=len(self.idle_resources)
                )
            else:
                # Pool full, cleanup
                await resource.cleanup()

    async def cleanup_old(self):
        """Cleanup old resources in pool"""
        async with self.lock:
            now = datetime.utcnow()
            active_resources = []

            for resource in self.idle_resources:
                age = (now - resource.created_at).total_seconds()
                if age < self.max_age_seconds:
                    active_resources.append(resource)
                else:
                    await resource.cleanup()

            self.idle_resources = active_resources


class ResourceManager:
    """Manages all resources with lifecycle and pooling"""

    def __init__(self, event_bus: EventBus):
        self.event_bus = event_bus
        self.resources: Dict[str, Resource] = {}
        self.session_resources: Dict[str, Set[str]] = {}
        self.pools: Dict[ResourceType, ResourcePool] = {}
        self.disposal_delay_seconds = 60  # Default disposal delay
        self._cleanup_task: Optional[asyncio.Task] = None
        self._running = False
        self._setup_event_handlers()

    def _setup_event_handlers(self):
        """Subscribe to lifecycle events"""
        self.event_bus.subscribe(EventType.SESSION_STARTED, self._handle_session_started)
        self.event_bus.subscribe(EventType.SESSION_ENDED, self._handle_session_ended)

    async def start(self):
        """Start resource manager"""
        if self._running:
            return

        self._running = True
        self._cleanup_task = asyncio.create_task(self._periodic_cleanup())
        log_info("✅ Resource manager started")

    async def stop(self):
        """Stop resource manager"""
        self._running = False

        if self._cleanup_task:
            self._cleanup_task.cancel()
            try:
                await self._cleanup_task
            except asyncio.CancelledError:
                pass

        # Cleanup all resources
        for resource_id in list(self.resources.keys()):
            await self.release(resource_id, immediate=True)

        log_info("✅ Resource manager stopped")

    def register_pool(self,

                     resource_type: ResourceType,

                     factory: Callable,

                     max_idle: int = 10,

                     max_age_seconds: int = 300):
        """Register a resource pool"""
        self.pools[resource_type] = ResourcePool(
            resource_type=resource_type,
            factory=factory,
            max_idle=max_idle,
            max_age_seconds=max_age_seconds
        )
        log_info(
            f"📊 Resource pool registered",
            resource_type=resource_type.value,
            max_idle=max_idle
        )

    async def acquire(self,

                     resource_id: str,

                     session_id: str,

                     resource_type: ResourceType,

                     factory: Optional[Callable] = None,

                     cleanup_callback: Optional[Callable] = None) -> Any:
        """Acquire a resource"""

        # Check if already exists
        if resource_id in self.resources:
            resource = self.resources[resource_id]
            resource.touch()

            # Cancel any pending disposal
            if resource.disposal_task:
                resource.disposal_task.cancel()
                resource.disposal_task = None

            return resource.instance

        # Try to get from pool
        instance = None
        if resource_type in self.pools:
            instance = await self.pools[resource_type].acquire(session_id)
        elif factory:
            # Create new resource
            if asyncio.iscoroutinefunction(factory):
                instance = await factory()
            else:
                instance = await asyncio.to_thread(factory)
        else:
            raise ValueError(f"No factory or pool for resource type: {resource_type}")

        # Create resource wrapper
        resource = Resource(
            resource_id=resource_id,
            resource_type=resource_type,
            session_id=session_id,
            instance=instance,
            cleanup_callback=cleanup_callback
        )

        # Track resource
        self.resources[resource_id] = resource

        if session_id not in self.session_resources:
            self.session_resources[session_id] = set()
        self.session_resources[session_id].add(resource_id)

        log_info(
            f"📌 Resource acquired",
            resource_id=resource_id,
            resource_type=resource_type.value,
            session_id=session_id
        )

        return instance

    async def release(self,

                     resource_id: str,

                     delay_seconds: Optional[int] = None,

                     immediate: bool = False):
        """Release a resource with optional delay"""

        resource = self.resources.get(resource_id)
        if not resource:
            return

        if immediate:
            # Immediate cleanup
            await self._dispose_resource(resource_id)
        else:
            # Schedule disposal
            delay = delay_seconds or self.disposal_delay_seconds
            resource.disposal_task = asyncio.create_task(
                self._delayed_disposal(resource_id, delay)
            )

            log_debug(
                f"⏱️ Resource disposal scheduled",
                resource_id=resource_id,
                delay_seconds=delay
            )

    async def _delayed_disposal(self, resource_id: str, delay_seconds: int):
        """Dispose resource after delay"""
        try:
            await asyncio.sleep(delay_seconds)
            await self._dispose_resource(resource_id)
        except asyncio.CancelledError:
            log_debug(f"🚫 Disposal cancelled", resource_id=resource_id)

    async def _dispose_resource(self, resource_id: str):
        """Actually dispose of a resource"""
        resource = self.resources.pop(resource_id, None)
        if not resource:
            return

        # Remove from session tracking
        if resource.session_id in self.session_resources:
            self.session_resources[resource.session_id].discard(resource_id)

        # Return to pool or cleanup
        if resource.resource_type in self.pools:
            await self.pools[resource.resource_type].release(resource)
        else:
            await resource.cleanup()

        log_info(
            f"♻️ Resource disposed",
            resource_id=resource_id,
            resource_type=resource.resource_type.value
        )

    async def release_session_resources(self, session_id: str):
        """Release all resources for a session"""
        resource_ids = self.session_resources.get(session_id, set()).copy()

        for resource_id in resource_ids:
            await self.release(resource_id, immediate=True)

        # Remove session tracking
        self.session_resources.pop(session_id, None)

        log_info(
            f"🧹 Session resources released",
            session_id=session_id,
            count=len(resource_ids)
        )

    async def _handle_session_started(self, event: Event):
        """Initialize session resource tracking"""
        session_id = event.session_id
        self.session_resources[session_id] = set()

    async def _handle_session_ended(self, event: Event):
        """Cleanup session resources"""
        session_id = event.session_id
        await self.release_session_resources(session_id)

    async def _periodic_cleanup(self):
        """Periodic cleanup of old resources"""
        while self._running:
            try:
                await asyncio.sleep(60)  # Check every minute

                # Cleanup old pooled resources
                for pool in self.pools.values():
                    await pool.cleanup_old()

                # Check for orphaned resources
                now = datetime.utcnow()
                for resource_id, resource in list(self.resources.items()):
                    age = (now - resource.last_accessed).total_seconds()

                    # If not accessed for 5 minutes and no disposal scheduled
                    if age > 300 and not resource.disposal_task:
                        log_warning(
                            f"⚠️ Orphaned resource detected",
                            resource_id=resource_id,
                            age_seconds=age
                        )
                        await self.release(resource_id, delay_seconds=30)

            except Exception as e:
                log_error(
                    f"❌ Error in periodic cleanup",
                    error=str(e),
                    traceback=traceback.format_exc()
                )

    def get_stats(self) -> Dict[str, Any]:
        """Get resource manager statistics"""
        pool_stats = {}
        for resource_type, pool in self.pools.items():
            pool_stats[resource_type.value] = {
                "idle_count": len(pool.idle_resources),
                "max_idle": pool.max_idle
            }

        return {
            "active_resources": len(self.resources),
            "sessions": len(self.session_resources),
            "pools": pool_stats,
            "total_resources_by_type": self._count_by_type()
        }

    def _count_by_type(self) -> Dict[str, int]:
        """Count resources by type"""
        counts = {}
        for resource in self.resources.values():
            type_name = resource.resource_type.value
            counts[type_name] = counts.get(type_name, 0) + 1
        return counts